362 SECRETION. 



may be collected in small quantity upon a glass slide and examined microscopically. It then 

 presents a number of strongly-refracting fatty globules, with a few epithelial cells. The 

 cells, however, are not numerous in the fluid as it is discharged upon the general surface ; 

 but, if the contents of the ducts and follicles be examined, cells will here be found in great 

 abundance. Most of the cells, indeed, remain in the glands, and the oily matter only is 

 discharged. The object of this secretion is to lubricate the general cutaneous surface 

 and to give to the hairs that softness which is characteristic of them when in a perfectly 

 healthy condition. 



It is only when the action of the sebaceous glands has become more or less modified, 

 that the secretion can be obtained in sufficient quantity for chemical analysis ; but we 

 cannot be certain that the fluid taken under these conditions is perfectly normal. The 

 analysis by Esenbeck, which is often quoted in works on physiology, was the result of an 

 examination of the contents of a largely-distended hair-follicle ; and, as the secretion was 

 confined for a long time, it is evident that it must have undergone material alteration. 

 We cannot, indeed, refer to any ultimate analysis of the normal sebaceous secretion ; but, 

 of all tho examinations that have been made of the secretion when it has been consider- 

 ably increased in quantity, those of Lutz give the best idea of what may be supposed to 

 be nearly its ordinary composition. This observer analyzed the secretion in a case of 

 general hypertrophy of the sebaceous system. The fluid which he extracted from the 

 dilated glands was milky-white, and of about the consistence, when cold, of wax. The 

 mean of eight analyses of this fluid was as follows : 



Composition of Sebaceous Matter. 



Water 357 



Oleine 270 



Margarine 135 



Butyric acid and butyrate of soda 3 



Caseine 129 



Albumen 2 



Gelatine 87 



Phosphate of soda and traces of phosphate of lime 7 



Chloride of sodium 5 



Sulphate of soda 5 



1,000 



This analysis gives the proportions of animal and solid matters, desiccated in a current 

 of dry air. Robin, who has reviewed at considerable length the analytical process em- 

 ployed by Lutz, regards the matter supposed to be either caseine or some analogous 

 albuminoid substance, as the organic matter of the epithelial cells that exist in such gre.it 

 numbers in distended sebaceous glands. He regards the weight of the substances desig- 

 nated under the names of albumen, caseine, and gelatine, with a certain quantity of the 

 water driven off by desiccation, as representing the proportion of epithelium. This view 

 is very reasonable, as the microscope always shows in these collections great numbers of 

 epithelial cells. Cholesterine, which is present so frequently in the contents of sebaceous 

 cysts, does not exist in the normal secretion, nor was it found in the analyses by Lutz. 



During the latter months of pregnancy and during lactation, the sebaceous glands of 

 the areola of the nipple become considerably distended with a grayish-white, opaque 

 secretion, containing numerous oily globules and granules. Frequently the fluid contains 

 also a large number of epithelial cells. During the periods above indicated, the secretion 

 here is always much more abundant than in the ordinary sebaceous glands. 



Smegma of the Prepuce and of the Labia Minorca, In the folds of the prepuce of the 

 male and on the inner surface and folds of the labia minora in the female, a small quantity 



